Process for the recovery of metallic values from slag



H. v. wELH PROCESS FOR THE RECOVERY OF METALLIC VALUES FROM SLAG Filed sept. 7. 1920 DoA mh E c R VZ O N e T 1w V. vl r r H V. B A f ,4 f

Patented yDec. 2, 1924.

UNITED STATES HAERYv. WELCH, oE'Los ANGELES, CALIFORNIA,- AssIeNoR To INTERNATIONALV `PRECIPITATION COMPANY, or Los ANGELES, CALIFORNIA, A .CORPORATION OE CALIFORNIA.

4.PROCESS Eon THE RECOvERY OE METALLIC vALI'IEs EROM siaAe.` l v Application lucaseptember` 7, 1920. aerialY N; 408,637.

To allwhmn it may concern;

Be it known that I, HARRY VWELCH, a citizen of the United States. residing at' Los ngeles, inthe county of Los Angeles, in I the Stateof California. have invented anew and useful Process `for the Recovery of Metallic Values from Slag (Case 13),' of which the following isa specification. n

Ina patent application of even date, Serial No. 408,636, I have disclosed a process and means of recovering a portion or allof the valuable metallicconstituents at present being discharged in the waste andmolten slags from metallurgical reduction works, l5 in particular copper and lead smelters, such process being based on the treatment of slag with a hal-idizing agent. i

For Vthe particular operation `in which -a fraction only of the metallic halogen compounds is volatilized after their formation, have devised'a recovery process which may be used or considered as supplementary or secondary to that described in said application above, and'of which the use of this sups lementary processpermits of much greater f exibility inthe application and control lof operations under the process.

Under certain conditions of` operation, such as would .present themselves where slags of acomple'x composition and unfavorable characteristics vfor release of volatile metallic halogen compounds which jhave been lformed as disclosed in said application, or where through the-necessities of 85 construction, a degree of cooling takes place in the molteny mixture of slag and halogeni bearing alkali or alkali earth so that proper evolution' of the halogen-bearing metallic salts Vis not fully obtained without `further D expenditure of fuel'to raise its temperature,V

or where it is not practical to introduce suicient as volume to wash out the metallic chlori e salts or vapors existing, I have found it ,possible to simply and economically extract the soluble metallic halogen compounds, -and under certainconditions, the metallic sulfates existing, by a' leaching process as hereinafter described.

V This invention may be carried out in any suitable type of apparatus, the accompanying drawing showlng an apparatus suitable for this purpose, said drawing being a vertical section of such apparatus.

The, apparatus shown in said drawing comprises one or more leaching agitating tanks 1 and 2, the first o f which is connected to receive the outflow or slag residue from avolatilization apparatus which ma befof any of thetypes disclosed in my app ication aforesaid, andv may, for example, as shown, consist of a tank 3 adapted to receive the slag to be treated from a furnace in settling tank indicated at 4, saidtank 3 being provided with means such as a pipe 5 for supplylng a metallic halide, such as sodium chloride, andwith a pipe 6 for supplying compressed air or other gas. Said tank is covered and has `an outlet y 7 for volatile products and an overflow spout 8-for residual slag. Said' leachingtanks 1 and 2 may be of any usual or suitable type or construction adapted to perform the operations hereinafter set forth'.

Above or in the upper part of theiirst tank 1, I provide-means'such as an air blast or gas blast pipe or nozzle 9 adapted to project a jet of air or other gas into the descending stream of slagresidue from outlet spout 8 of the'tank 3, so as to break up said slag residue into fine particles asA hereinafter set forth. Means such as a pipe or nozzle 10 are also provided fork injectmg a jet of water. or solution into the descending particles, this nozzle 10 being preferably beow the nozzle 9 although the may be c0- axial if desired. The tank 1 1s adapted to contain a body of .water or solution indicated at 11, into which the finely divided or brokenV up particles orjgranules of slagl residue fall and are subjected -to leaching action. l y

An elevator 12 may be provided. for lifting the solids from4 the bottom ofVv tank'l to the top of the next tank 2,-wherein they are subjected to a further leaching operation, or to washing,l as the case may be. An elevator 13 lifts the solids from the bottom of the second tank to a. succeeding tank or to tailings receiving means." Fresh water for washing may be supplied to thetailingsoutletof thelasttank, by pipe 14. Leaching solution may be returned. from tank 2 to tank 1 b pumpl whose inlet pi e 16 is connecte to tank 2 and Vwhose out etv pipe 17 leads to nozzle 10 aforesaid. Pregnant solution is conducted from tank 1 by overflow pipe 18 to any suitable precipitation tank or metal recovery apparatus 19.

The process may be carried out as followsz-,The molten slag coming from a metallurgical furnace, or other apparatus, may `first be treated in tank 3 by addition thereto or contact therewith of sodium chloride, or other metallic `halogen ycompound, or equivalent material, and agitation with air or with furnace gases, and with steam or water vapor if required.'so as to volatilize a portion ofthe metallic values therein inthe form of halogen com ounds;

whichpass oil' with the 'gases throug outlet 7 and are collected in any suitable manner, for example, by electrical precipitation, or in bag houses, or spray towers. The residual slag overflows Vat outlet 8 rforminga descending stream of molten slag, which in the present case is assumed to contain a portion `or fraction of the metallic values of the particles or granules, which may take a form dependent` on the temperature, the relative quantity and velocity of the air or gasblast compared with the massofdescending slag, the pressureof theblast, and so forth, the particles or granules forming fine'pellets or shot like formation, orvesicular capsules, ora fibrous wool pro-v cluct,sas the jcase may be. vUnderv certain conditions, that is when the, gas volumeof blast is insuiiicient to remove enough heat from. the slag particles to chill or bring them to solid form. it may be necessary to introduce belowvor adjacent to ,the air or f gas blast, by means of .nozzlel 10 a` spray v of water or solution to cool the particles to solid state.A ,The minute particles of solidl slag are then caught in the-body 11 4of water orv solution in vtank ,1, wherein the are subjected to .leaching operation an from this tank the solid material yis removed tothe next tank of the series, the solid material moving in op osite ldirection Atofthe ,flow of 'water lor so utionthat is,

in counter current operation, by which means the most 4,effective and economical leaching operation is secured.

Various ,solution agents may be used in the leaching operation described 'depending on the nature ofthe soluble values ex- Y isting vashalogen compounds in the slag granules. For example, if cuprous choride or lead zchloride ,be present a brine solutionv may 'be used as an extraction agent. If copper 1s present inl the form of an oxychloride or basic salt an acid solvent may be necessary to properly leach it. If silver chloride is present, a solution of solium thiosulfate may be advantageousl used. Should lead values a pear as sul ate, an acetate solution woul prove desirable for its extraction. After leaching the material in this manner in any desired number of stages it may be washed in the final tank, the dilute solution from which is pumped back to the first tank.

What I claim is:

1. The .process of recovering metallic values from molten metallurgical slag, which consists in bringing said slag, while still molten, in contact with a Ihalidiaing agent in anoxidizing atmo here so as to form volatile compounds with a metallic constituent of the slag, collecting the material thus volatilized from the slag and subjecting the slag residuel to leachn operation to recover metallic values there rom.

2. The process' which consists in subject ing molten slag containing metallic values to, the action of a halidiz'ing agent to produce vsoluble metallicfcompounds, causing the resulting product while in a molten condition to descendA in a stream, vsubjecting such stream to the action of a jet of gas` to cause the' `stream of molten slag to be ysubdivided into a stream of finely divided licuid particles, cooling said particles to so id state, and subjecting said particles to leaching operation to recover the soluble constituents of value contained therein.

3. The process of recovering metallic,

.ized from the slag, causing the residual slag to be subdivided into fine particles and subjecting such particles to leaching opera tion with a'sultable solvent, for recovering metallic values therefrom.

4. A rocess, as set forth in claimt, in which t 1e slag is subjected to the action of water vapor in addition to the action of exygen to aidin the formation f i volatile compound. e

5.. A process, as t which water vapor is brought into contact with the melted slag to aid in the,formation of a volatile compound.

In testimony whereof I have hereunto subscribed my name this 19th day of August, 1920. l

HARRY V. WELCH.'

forth in claim aan lll 

